Fountain pen



March 17, 1970 v 1.. P. MARTIN ETAL FOUNTA IN PEN 2 Sheets-Sheet 1Original Filed July 22 1965 lullllllll IIIIIIIIIIII \i! u J 4 1 l lllllll III III March 17, 1970 L. P. MARTIN ETAL FOUNTAIN PEN 2Sheets-Sheet z Original Filed July 22, 1965 United States Patent3,501,225 FOUNTAIN PEN Lynn P. Martin and Thomas P. Evans, Fort Madison,Iowa, assignors, by mesne assignments, to Textron, Inc., Providence,R.I., a corporation of Rhode Island Continuation of application Ser. No.474,083, July 22, 1965. This application July 19, 1968, Ser. No. 755,485Int. Cl. B43k 5/18 US. Cl. 401-198 8 Claims ABSTRACT OF THE DISCLOSUREIn a novel fountain pen having a vacuum type ink reservoir, a writing ormarking point, and a capillary ink feed; an improved fluid controlmember arranged for releasably retaining ink to prevent leakage from thepoint in the event of excess ink discharge from the reservoir. The fluidcontrol member comprises a porous plastic matrix, wettable by writingfluid, and defining a multiplicity of interconnected randomly disposedcapillary storage cells of irregular configuration communicating withthe atmosphere, with one another and with the ink feed means. Thestorage cells are lower in capillarity than the ink feed and normallyremain free of fluid. In operation, ink is drawn from the reservoir bythe ink feed and transferred directly to the point for deposit on awriting surface. In the event excess ink enters the feed, however, suchink will be transferred to the control member for retention in thestorage cells until the feed requires additional ink for writing. Ascompared with the usual comb cut type control member, the presentcontrol member provides significantly greater fluid storage efficiencyand is substantially less costly to manufacture while being considerablyless susceptible to breakage during manufacture and assembly.

This application is a continuation of our earlier application Ser. No.474,083 filed July 22, 1965 for a Fountain Pen, now abandoned.

This invention relates to a writing instrument and more particularly toa fountain pen having improved ink feed control means.

In the usual fountain pen construction, ink is contained in a reservoirthe internal volume of which remains substantially constant duringnormal writing use of the pen. If continuous writing is to be realized,it is necessary to provide for the controlled entry of air into thereservoir to relieve the slight vacuum created therein by the withdrawalof ink therefrom during writing. This simultaneous but opposite flow ofair into and ink out of the reservoir is generally accomplished throughcontiguous air and ink channels formed in or at least defined in part bya feed bar which extends between the reservoir and the point. The inkchannel usually is formed as a relatively tight capillary slit orfissure in the feed bar with the air channel usually being the spaceimmediately adjacent the feed bar. The air channel is small enough incross section to support a column of ink but large enough to permit themovement of air bubbles therethrough.

Any air in the fountain pen reservoir will, of course, tend to expand ifthe pen is subjected to a temperature increase or an atmosphericpressure decrease. If such expansion should occur while the pen is heldpoint downwardly, as in writing, ink may be forced from the reservoir inan amount greater than that which can be accommodated in the ink and airchannels.

In the past, manufacturers have incorporated into their pens what mightbe termed an expansion chamber to control or accommodate such excess inkflow and to prevent 3,501,225 Patented Mar. 17, 1970 ice leakage of inkfrom the pen. The expansion chamber has customarily taken the form of aplurality of relatively large capillary size grooves or comb cutsmachined in the feed or in a separate control member adjacent the feed,the grooves being arranged to communicate both with the ink feed channeland the atmosphere. With such a construction excess ink entering the inkfeed channel will overflow into the expansion chamber grooves fortemporary storage until such time as it is returned to the feed channeleither for replacement of ink withdrawn during writing or for return tothe reservoir after the inkexpelling pressure in the reservoir has beenrelieved.

Without question, known expansion chamber devices have proven to be ofdefinite value in the fountain pen art, substantially reducing many ofthe severe leakage problems which were inherent in early day fountainpens. However, these expansion chamber devices have given rise toseveral additional problems which manufacturers have assiduouslyattempted to solve over the years without significant results, forpresent day fountain pens still utilize the same basic structuresdevised many years ago. For example, whether machined from hard rubberor molded from a suitable plastic, these expansion chamber devices arerelatively expensive because of the complicated precision machinery,skilled workers and time consuming operations needed in holding theextremely close tolerances involved in their production. Moreover, evenwith the best manufacturing techniques and equipment, it is difficult tomaintain these close tolerances, and any significant deviation incertain of the essential dimensions of these devices will often make thedifference between proper and improper functioning of the pen.

Also, because of the fragile nature of the combs and other parts of theconventional expansion or fluid control devices, a high percentage ofthe devices usually are damaged either during processing or while beingassembled into finished pens. Accordingly, not only is production timeof highly skilled workers lost,'but such damaged controls cannot be evenpartly salvaged.

Another drawback to the usual expansion device is that a good percentageof its total volume is solid and therefore not available for holdingink. The high percentage of solid material in such devices serves merelyas support for the capillary grooves so that the resulting structurewill not be excessively fragile. Although manufacturers have tried invarious ways to more efliciently utilize the volume occupied by theexpansion device, very little progress has been made up until thepresent time. Thus, of the already limited available interior space inpresent day quality pens, a fairly significant portion thereof will beoccupied by the expansion device which must be of sufficient size toprovide an adequate reserve overflow capacity for the pen. Heretofore,if the size of the expansion device were to :be reduced to provide adesirable increase in the reservoir capacity, for example, amanufacturer would risk the creation of a condition which could lead tocustomer complaints because of leakage. With the usual fountain pen itthus has been a real problem to arrive at a satisfactory balance betweenreservoir and overflow capacities.

The present invention represents the first commercially significantimprovement in fountain pen feed control systems since manufacturersadopted the concept of providing capillary overflow grooves many yearsago. This invention not only eliminates or substantially alleviates theseveral problems discussed hereinabove but at the same time provides asignificant reduction in both manufacturing and repair costs.

Accordingly, it is a principal object of the present invention toprovide an improved feed control member for a fountain pen.

Another object of this invention is the provision of an improved feedcontrol member which consists of a single part that may be easily andinexpensively manufactured.

It is yet a further object of this invention to provide a greatlysimplified and completely reliable fluid control member having amultiplicity of overflow cells or chambers distributed randomlytherethroughout.

A still further object of this invention is the provision of an improvedfountain pen fluid control member consisting of a molded plastic matrixhaving distributed randomly therethroughout a multiplicity ofintercommunicating capillary overflow cells adapted to temporarily holdexcess ink discharged from the reservoir.

Yet another object of this invention is to provide a fountain pen of thetype having a vacuum ink reservoir, the pen including a molded plasticfluid control member which is much less fragile than previous controlsand has a very high ink holding capacity for its size.

A still further object of the present invention is the provision of afountain pen having an improved fluid control member comprising a moldedplastic matrix having distributed randomly therethroughout amultiplicity of various size intercommunicating spaces, a portion ofsuch spaces serving as fluid transfer channels with the rest of suchspaces serving as overflow storage cells for receiving and temporarilyholding any excess ink discharged from the reservoir.

Yet an additional object of the present invention is to provide a fluidcontrol member which is extremely simple yet highly eflicient, which isinexpensive yet reliable, and which can be routinely handled andassembled by the manufacturer without danger of damage thereto.

Still further objects and advantages of the present invention will beapparent from the following description and the accompanying drawings.

According to the present invention, there is provided a fountain penhaving a barrel with a conventional ink reservoir disposed therein.Extending forwardly of the barrel is a writing point, which may be anyone of several different kinds, and a capillary feed extends between andsupplies ink from the reservoir to the point. Carried by the barreladjacent the feed is a control member comprising a porous matrix whichis wettable by the ink and which defines a multiplicity of randomlydisposed ink storage cells communicating with the atmosphere and withthe feed. These storage cells are lower in capillarity than the feed,and while they normally are not filled with ink, they have sufficientcapillarity to support ink which might be received therein from the feedunder conditions of excess ink discharge from the reservoir. Because oftheir lower relative capillarity however, any ink contained in the cellsis released readily to the feed upon subsequent removal of ink from thefeed, and thus the cells serve only to temporarily store fluid forcedfrom the reservoir during such periods of excess ink discharge.

For a more complete understanding of this invention reference should nowbe had to the drawings, wherein:

FIGURE 1 is a longitudinal sectional view of a fountain type marking penembodying the present invention;

FIG. 2 is a front end elevational view of the pen of FIG. 1;

FIG. 3 is an enlarged longitudinal view, partially in cross section, ofthe feed control member of the embodiment of FIG. 1;

FIG. 4 is a front end view of the fluid control member as shown in FIG.3;

FIG. 5 is a longitudinal sectional view of the forward portion of a penconstituting another embodiment of the present invention;

FIG. 6 is a transverse sectional view of the embodiment of FIG. 5 takenalong line 6-6 of that figure; and

FIG. 7 is an exploded perspective view of the feed and feed controlmember of the embodiment of FIG. 5.

Referring now to the drawings and more particularly to FIGS. 1 through 4thereof, there is illustrated a fountain pen 10 having a generallycylindrical barrel 12 which may be molded of plastic. A forward barrelportion or gripping section 14 is threadedly mounted in axial alignmentwith the barrel 12, as by threads 16, to permit convenient disassemblyof the barrel and gripping section for filling purposes.

As will be seen best from FIG. 1, the gripping section 14 is of agenerally cylindrical configuration with a gradual inward taper towardits outer or forward end to provide a pleasing appearance and acomfortable gripping area for the user.

The ink or fluid reservoir in this embodiment is of the conventionalvacuum type, consisting of a throwaway cartridge 32 which is molded of aplastic material having low moisture vapor transmission characteristics,such as polypropylene or polyethylene. This cartridge includes acylindrical body portion 34 having one end closed by an integral wall36, and the other end sealed by a closure plug or disc 37. Preferably,both ends 36 and 37 of the cartridge 32 are adapted to be pierced sothat the user does not have to orient the cartridge when inserting itinto the pen.

The inner end of the enlarged gripping section bore 48 is closed by aplug 38 having an enlarged rearward flange 40 which in the illustratedembodiment abuts against and seats on the rearward end of the grippingsection. This flange 40 not only provides for the convenient positioningof the plug relative to the gripping section, but it likewise enablesthe plug to be sealed readily to the gripping section by spin weldingshould such sealing be desired.

Press fitted into a central longitudinal bore 42 in the plug 38 is apierce tube 44 having a bias cut on its rearward end, this cut providinga piercing point 46 which is sufficiently sharp to penetrate either thewall 36 or the plug 37 of the cartridge 32 upon insertion of thecartridge into the pen for purposes of renewing the ink supply.

A centrally disposed longitudinal reduced bore 50 (see FIG. 2) extendsforwardly from the large bore 48 of the gripping section 14, thisreduced bore 50 terminating at the outer end of the gripping section toprovide therein an open forward end. Extending radially into the bore 50from the bore-defining walls of the gripping section 14 are severallongitudinally extending splines or ribs 52 which serve to furtherrestrict the effective diameter of the reduced bore 50.

While other types of points may be used with this invention, the point54 in this embodiment is a substantially rod-like element of generallycircular cross section and it is formed of a porous plastic material ofthe type disclosed in copending patent application No. 244,196, filedDec. 12, 1962, the matrix preferably being a polyamide such as afluorocarbon. The point 54 includes (1) a writing tip portion 56 whichextends through the reduced bore 50 of the gripping section andforwardly therebeyond for writing purposes and (2) an integralrearwardly projecting elongate feed portion, which in the embodimentillustrated in FIG. 1 consists of an intermediate section 58 disposed inthe bore 48 and a reduced section 60 which extends through the piercetube 44 to adjacent the piercing point 46 thereof. Thus, the point 54 ineffect constitutes a capillary ink conductor for feeding ink from thereservoir 32 to the writing tip 56, this feeding conductor comprisnig amultiplicity of interconnected pores ranging from about .001 inch toabout .006 inch in diameter as measured by standard ASTM pore sizedetermination methods.

Referring generally to the size of the pores of the point 54, it will berecognized that individual pores may vary in size either below or abovethe diameter mentioned heretofore, without any adverse effect on theperformance of the point. However, for proper capillary feeding of theink, a major portion of the pores should fall within or average close tothe specified range when used with the standard type of aqueous basedwriting ink.

For best performance, it will be understood that the point 54 preferablyshould be manufactured of a material which is wettable by the usualwrinting ink or which can be made wettable either by treatment with asurface active agent or by exposure to the ink itself.

The point 54 is maintained in proper operating position in the grippingsection assembly by means of frictional engagement of the Writing tipportion 56 thereof by the radially extending splines 52 in the reducedbore 50 of the gripping section 14. The diameter of the bore 50 isgreater than the diameter of the writing tip portion 56 but theeffective diameter of the bore 50 is actually reduced by the radialsplines 52 to slightly less than that of the tip portion 56, so that thefrictional engagement therebetween is tight. In spite of this tightfrictional engagement between the splines 52 and the tip 56, ventingfrom the atmosphere to the interior of the gripping section is providedthrough the bore 50 along the periphery of the tip 56 in the spacesbetween the splines 52.

Disposed within the gripping section 14 and arranged for fluidcommunication with the elongate feed portion of the point 54, is animproved fluid control member 62, this control member being generallycylindrical in configuration to conform to the interior surface of thegripping section bore 48. As will :be seen from FIGS. 1, 3 and 4 of thedrawing, this fluid control member 62 includes a longitudinallyextending central bore 64 which is slightly larger in diameter than theadjacent intermediate section 58 of the feed. For example, if theintermediate section 58 of the feed measures .075 inch in diameter, thebore 64 of the feed 62 preferably should be about .082 inch. Further,the diameter of the bore 64 preferably should be slightly smaller thanthe outside diameter of the pierce tube 44 so that the portion of thepierce tube 44 extending forwardly of the plug 38 may be press fittedthereinto (see FIG. 1). This latter feature is suggested primarily forconvenience in manufacture as it will allow the plug 38, pierce tube 44and control member 62 to be preassembled before insertion into thegripping section 14 as a complete subassembly. In this connection, itshould be noted that the feed control preferably is short enough that itdoes not make contact with the rerawardly facing shoulder 66 formed bythe intersecting forward and intermediate bores 50 and 48, respectively,of the gripping section 14.

From the above description, it will be seen that the feed sections 58and 60 provide a fluid conductor for the direct transfer of ink from thereservoir to the writing tip 56, with a return air channel beingprovided through the bore 50 surrounding the writing tip 56, through thespace between the forward end of the feed control 62 and the shoulder 66and rearwardly along the feed portions 58 and 60 between their outerperiphery and the inner surfaces of the adjacent feed control member 62and pierce tube 44. Since ink will usually be present in the piercetube, as writing progresses, a slight vacuum is created in the reservoir32, which vacuum causes minute air bubbles to be drawn through the airchannel just described to relieve this vacuum and permit continuedfeeding of ink from the reservoir for writing.

As discussed briefly h-ereinabove, the usual feed control memberincludes a plurality of machined comb cuts, or equivalent structure, forthe temporary storage of fluid which might be forced from the reservoiras a result of a pressure increase therein. With the present invention,the complexity and high costs attendant to the manufacture of suchcontrol members have been eliminated while at the same time providing anincrease in operating efiiciency and durability. These and other verysignificant advantages are realized by the provision of a feed controlmember consisting of a plastic matrix which defines therethroughout amultiplicity of randomly disposed ink storage spaces or cells whichcommunicate with one another and with the atmosphere,

and which at least under conditions of flooding communicate with thefeed conductor extending between the reservoir and the writing tip. Aswill be best seen from FIGS. 1, 3 and 4 of the drawings, communicationbetween these cells and the atmosphere is provided through a generallysemicylindrical venting channel 68 formed longitudinally along thelength of the fluid control 62. This venting channel 68 thencommunicates with the atmosphere through the spaces :between the splines52 surrounding the tip 56 in the reduced bore 50 as previouslydescribed.

The control member 62 is formed as a unitary homogeneous porous matrixof a synthetic plastic material of a type which is wettable or which canbe made wettable by the usual fountain pen ink. Other materials can beused for this control member, including both inorganic and organic solidparticles inert to ink and capable of being bonded or otherwise attachedtogether, but polypropylene is preferred. The control member 62 consistsof a multiplicity of particles of material which are bonded together attheir points of contact, the size of these particles being chosen toprovide the cell dimensions discussed in more detail hereinbelow. As oneexample of a process of forming these particles into a control member,they may be lightly packed into a molding die of the desiredconfiguration with the die then being heated sufficiently to causesoftening and subsequent bonding together of the surface contactingportions of the particles. Upon subsequent cooling, the particles remainbonded together to form the necessary unitary homogeneous porous matrix.The amount of heat used in this process depends, of course, upon theparticular material chosen for the particles, as the heat employed inmelting the exterior surfaces of one type of material may causeinsuflicient or alternately complete melting of another material. Thus,for the particular particulate material chosen, it would usually benecessary to conduct a few routine tests to determine the amount andtime of heating and the pressures needed for the initial lightcompacting of the particles.

The spaces in the feed control member 62 are randomly distriubuted andof various sizes. The total volume of these spaces, herein referred toas void volume, is preferably in the range of about 40% to about 75% ofthe total volume of the control. If the void volume falls below about40% the capacity of the feed is generally considered too low, and if thevoid volume exceeds about 75 with present materials and methods thesupporting structure appears to be too fragile. A certain percentage ofthese spaces or voids, ranging from about 10% to about 60% of the totalspaces, comprise fluid storage cells the width of which range frombetween about .01 inch to about .07 inch. Cells within this size rangefill with fluid only during periods of excess ink discharge from thereservoir 32, and subsequently release such fluid readily to the highercapillarity of the pores of the point 58 either during subsequentwriting or as fluid is pulled back into the reservoir upon reduction ofthe pressure therein.

The Width of the fluid conducting smaller spaces in the fluid control 62may range from about .001 inch to about .01 inch. These smaller spacesform a vein-like network of capillary passages through which ink isremoved as rapidly as it is exuded from the intermediate section 58 ofthe feed during periods of excess ink flow or flooding. By means of thesmaller spaces in the fluid control, ink is efficiently distributedthroughout the control member 62 to the storage cells 67. This vein-likeI It will be understood by those in the art that the dimensions of thespaces in the point 54 and in control member 62 may have to be varied,depending upon the character of the ink used in the pen, and Wettabilitycharacteristics between the ink and the porous matrix. However, with acontrol member having proper Wettability and the usual aqueous based inkhaving a surface tension ranging from about 40 to 60 dynes percentimeter and a viscosity of about 1 centipoise, the above discussedsizes have proven satisfactory.

Depending upon the material chosen for use in forming the matrix of thecontrol member 62, the finished control may have to be treated toimprove its Wettability with the ink to be used in the pen. For example,it has been found that a polypropylene matrix should be treated with asurface active agent to insure proper operation when initially put intouse. One such suitable agent may be prepared as a solution of 99% water,.5% Span 80 (sorbitan monooleate) and .5% Tween 80 (polyoxyethylene (20)sorbitan monooleate) which are products of the Atlas ChemicalIndustries, Inc., of Wilmington, Del. It has been found that immersionand agitation of the fluid control 62 in such a solution, and subsequentdrying, will give a surface which is quite satisfactory insofar asWettability is concerned. Alternately, it has been found that apolypropylene control member can be made adequately wettable byimmersion thereof in the writing fluid with which it is to be used for aperiod of several days.

Wettability of a particular material by a specific liquid generally isdefined by a contact angle designation. It has been found that thecontact angle of certain inks having a surface tension of between about40 and about 70 dynes per centimeter will form a contact angle on aclean solid polypropylene surface of about 80 to 100. The contact angleon the small particles used in making the untreated polypropylenecontrols as discussed above is more difficult to establish, but it isbelieved to be in the same area of 80 to 100. This would appear to betoo high an angle for proper initial Wettability of the controls, and areduction therein, by a surface active agent or lengthy immersion in theink, is believed desirable. A contact angle of below about 50 wouldappear to be suitable for the present controls, although, of course, theangle should be brought down as much as possible.

As will be understood from the above description, the present embodimentoperates in its feeding and venting in much the same way as a regularfountain pen with ink being withdrawn from the reservoir through thefeed or point 54 for deposit on the writing surface and with airentering the reservoir through the previously described vent channel toreplace the fluid thus used. Should expansion of air occur in thereservoir when the pen is held downwardly, excess ink will be exudedfrom the feed and forced into the space surrounding the feed. Thisexcess will quickly transfer to and throughout the fluid control member62 passing by way of the smaller veinlike spaces to the larger fluidstorage cells thereof. During this transfer and distribution, airdisplaced from the control member will be vented to the atmospherethrough the venting channel 68 and thence through the spaces in the bore50 surrounding the writing tip 56. The ink thus deposited in the storagecells will be safely retained against loss until such time as it iswithdrawn back to the writing point either during subsequent writing oras the air in the reservoir contracts and the pressure therein is thusrelieved.

Referring now to the embodiment of FIGS. 5 through 7, there is discloseda fountain pen 100 having a feed control member similar to thatdescribed hereinabove with respect to the first embodiment, except thatthe control member is used in conjunction with a slitted metal point anda hard rubber feed of the usual type.

This modification consists of the fountain pen having a barrel 102 withforwardly disposed internal threads 104 for engagement with a rearwardlyextending reduced threaded portion 106 of the gripping section 108. Thebarrel 102 and gripping section 108 may be molded of a suitablesynthetic thermoplastic resin.

As will be noted, the barrel 102 has an enlarged intermediate bore 110of about the same diameter as the rearwardly opening enlarged bore 112in the gripping section 108. The barrel bore 110 and gripping sectionbore 112 thus comprise a cavity for the reception of a throwaway typeink reservoir or cartridge 114 which abuts rearwardly against the barrelshoulder (not shown). It will be understood, of course, that otherreservoir arrangements may be utilized in this pen, such as a plunger orlever filling mechanism of the usual type, but for simplicity purposes acartridge reservoir has been illustrated.

The gripping section 108 preferably is generally circular in crosssection, with a gradual inward taper toward the front of the pen and agenerally hooded design for convenient gripping and an aestheticappearance. Internally, the gripping section is provided with anintermediate bore 118 extending forwardly of the rearward bore 112 toprovide a rearwardly facing shoulder 120. As will be noted particularlyfrom FIG. 4, the bore 118 tapers inwardly somewhat toward the forwardend, terminating in a further reduced forward bore 122 which extendsthrough thef orward end of the gripping section.

A plug 124 is press fitted into bores 112 and 118, the plug including arearward enlarged flange 126 adapted to abut the gripping sectionshoulder for positioning purposes. The earward face of the plug includesa screw driver slot 128 for purposes of orientation of the plug as wellas for use in spin-welding the plug to the gripping section should suchattachment be desired by the manufacturer. Extending rearwardly of theplug 124 is a pierce tube 126 which, while being illustrated as integralwith the plug, nevertheless may be of a type adapted for assembly withthe plug in a manner well known in the art. Further, if the plug is of amolded type, it may be desirable for the manufacturer to provide anannular cut or indentation 130 extending rearwardly from its forwardface, this out not only serving to reduce the amount of material in theplug but also to provide some resilience in the plug 124 for providing agood press fit in the bore 118. The pierce tube terminates on itsrearward end on a bias cut providing a piercing point 132 which willpenetrate either end of the reservoir cartridge 114 upon assembly of thecartridge into the pen.

The feed bar or feed means 131 in this pen includes a forward headportion 134 having an enlarged annular flange 136 adapted to abut andposition against the rearwardly facing shoulder 138 formed at theintersection of the gripping section bores 118 and 122. Extendingforwardly of the flange 136 is a generally circular tapering noseportion 140 having a land 142, the purpose of which will be hereinaftermore fully described.

Extending rearwardly of the head portion of the feed 134 is asubstantially cylindrical hollow tail portion 144, the upper surface ofwhich has a longitudinal slot 146. As will be noted, the tail portion144 extends rearwardly into a forwardly facing opening 148 in the plug124 to thereby align with the pierce tube 126 and to provide with thepierce tube a continuous conduit through the pen from the bias cut endof the pierce tube 126 to the nose portion 140 of the feed 131.

Mounted in this channel formed by the pierce tube and feed tail is afeed insert 150 which is provided with a longitudinally extendingflattened bottom area 152 (see FIG. 6) and a contiguous capillaryfissure 154 which extends upwardly from the flattened area 152. Thisfissure 154 is cut completely through to the top of the insert at theforward end of the insert 150, but is not cut com pletely through in theremaining rearwardly extending portion of the insert. It will be notedthat the insert 150 is positioned in the upper portion of the feed tail144 to close slot 146 except for communication through the fissure atthe forward end of the insert.

A capillary slit 156 is formed adjacent the forward end of the feed noseportion 140. This capillary slit 156 communicates with the capillaryfissure 154 in the insert 150 to provide a continuous capillary fluidchannel from thelnose portion 140 of the feed to the ink reservoir 114.

Disposed on the land 142 of the feed head 140 is the rearward ormounting portion 158 of a pen point 160. This pen point is preferablyformed of a gold or stainless steel alloy and. provided with a forwardwriting tip portion 162 having the usual capillary slit formed betweentwo relatively flexible nibs.

The point 160 is held in proper operating position by a press fitbetween the interior surface of the gripping sectiofi forward bore 122and adjacent surfaces of the feed land 142, with sufficient space beingprovided between the nibs-of the point and the interior of the grippingsection to permit a limited amount of flexure of the tip 162 duringwriting use.

As heretofore described this pen operates in a conventional fashion,fluid being drawn from the reservoir and into the capillary fissure 154of the insert 150, then being transferred to the capillary slit 156 ofthe feed and finally to the capillary slit of the writing tip 162 fordeposit on a writing surface. As such feeding occurs, air is drawn intothe reservoir through an air scoop 164 in the head 140, then through atransverse aperture 178 in the lower section of the feed extension 144and finally through the enlarged air passage 166 formed between the flatarea 152 of the insert 150 and the internal surface of the extension ortail 144.

Disposed in the intermediate bore 118 of the gripping section 108 and insurrounding engagement with the feed tail 144 is an improved feedcontrol member 170 constrticted according to the present invention. Aswill be noted from the drawing, this control member 170 is generallycylindrical in configuration, tapering slightly toward the front toconform with the tapering internal configuration of the intermediatebore 118. The internal bore 172 of the feed control member 170preferably is of about the same diameter as the diameter of the feedtail 144 whereby the control member 170 can be pushed onto the feed tail144 and into engagement with an abutment 174 onthe head 140 forpositioning purposes, and the feed 131, the writing tip 162, the insert150 and the control member 170 may be assembled into the grippingsection 108 as a complete subassembly.

The control member 170 is similar in structure and function to thecontrol member 62 of the previously described embodiment illustratedparticularly in FIGS. 3 and 4. Basically, this control member comprisesa homogeneous porous matrix formed of a synthetic plastic materialpreferably, but not limited to, polypropylene, the material beingnonreactive with but wettable by the usual writing fluid. If necessary,this wettability can be improved in the various ways previouslydiscussed.

As with the first embodiment, the control member 170 defines amultiplicity of randomly disposed fluid storage cells ranging from about.01 inch to about .07 inch in width. As will be understood, these cellsare substantially lower in capillarity than the capillary fissure 154 ofthe insert 150 and, therefore, will not draw fluid from this feedfissure during normal use of the pen. Thus, except perhaps for the tightcapillary dimensions at the juncture of the particles forming the cells,the cells will be clear of fluid and available for accommodating anydischarge of excess fluid from the reservoir into the capillary feedfissure 154 and air channel 166. In the event of such a discharge,excess ink will be forced through the fissure 154 of the insert 150 andinto the groove 146 of the feed extension 144 from where it will bepicked up by the feed control member 170 and distributed rapidlytherethroughv of the head portion 140 of the feed which, in turn, is in'10 out to the storage cells by the small vein-like network of cells ofhigher capillarity interspersed between the storage cells.

It will be understood, of course, that it is preferable to provide asmany storage cells as possible in the fluid control 170. Depending uponthe manner in which the control member 170 is made, and the particulatemate'- rial used in forming the matrix, the percentage of such storagecells (of a size between about .01 inch and about .07 inch in width)generally will range from between 40% to about of the total void volumeof the control member. Generally, however, such storage cells will rangebetween about 50% to about 70% of the void volume of the control. Therest of the void volume will consist of the smaller spaces, whichgenerally range up to about .01 inch in diameter. The total void volumewill range from about 40% to about 75% as indicated for the feed control62 of the previously described embodiment.

Depending upon their size, a portion of the smaller spaces may remain atleast partially full of writing fluid during normal usage of the pen.And while this factor will somewhat reduce the ultimate capacity of thecontrol member 170; these pre-wet or prefilled spaces have the advantageof permitting more rapid removal and transfer of ink than wouldotherwise be realized. Also, they are believed to insure better and morerapid distribution of ink throughout the control member 170, especiallyto the upper or rearward end thereof, which is highly desirable in astructure as illustrated where communication between the feed fissure154 and the control member 170 is restricted to one end thereof and afairly long distance must be traversed by the ink to fill the storagecells at the opposite end of the control member 170.

It will be understood that the storage cells have to be in communicationwith the atmosphere and in the present embodiment such communication isprovided by the venting channel 182 which runs the full length of thecontrol member 170. This venting channel is in communication with theair scoop 164 formed along the lower surface direct communication withthe atmosphere.

As Will be understood from the above description, the operation of thepen might be considered conventional to the extent of the feeding offluid from the reservoir to the point and the return of air to thereservoir to replace fluid used during writing. However, the structureprovided for accommodating excessive ink discharge from the reservoir isgreatly improved over the usual prior art devices. This fluid controlmember provides a number of unique new advantages and features. Forexample, it is manufactured in a very simple, inexpensive mold; it usesa minimum of material, consisting principally of storage spaces; itrequires no subsequent machining; it can be inspected very readily forquality control purposes, having no intricate combs, fissures, etc.; itcan be handled and assembled with little or no danger or breakage ordamage; and, it is highly efiicient whereby for a given amount of space,it Will provide a greater storage capacity than the usual controlmember.

It will be understood from the above description that the presentinvention is not to be limited to the embodiments herein described butthat it is applicable to other types of writing instruments and similardevices.

What is claimed is:

1. In a fountain pen having a barrel with a vacuum type ink reservoirtherein, a point extending forwardly beyond said barrel, and a feeddefining a capillary conduit for supplying ink from said reservoir tosaid point; a control member carried by said barrel forwardly of saidreservoir, and control member comprising a matrix (1) wettable by saidink,

(2) provided with a transfer surface disposed adjacent to said capillaryconduit, and

(3) defining a multiplicity of ink storage cells.

(a) of irregular configuration, (b) communicating with one another, (c)randomly distributed throughout said matrix, ((1) larger in width andlower in capillarity than said capillary conduit, but (e) havingsufficient capillarity to support ink re ceived therein, and (f)comprising substantially the entire ink storage capacity of said controlmember, an element disposed between the rearward portion of saidtransfer surface and said capillary conduit, said element providing withsaid conduit an air channel communicating with said reservoir and withthe atmosphere, a portion of said cells being intersected by saidtransfer surface to provide communication between said cells and saidcapillary conduit forwardly of said element, and means intersectinganother portion of said cells for venting said cells to the atmosphere,said cells receiving ink through said transfer surface forwardly of saidelement and dis lacing air through said vent means under conditions ofexcess ink discharge from said reservoir into said conduit, said cellsreadily releasing ink to said conduit upon subsequent removal of inkfrom said conduit whereby said cells remain substantially empty exceptduring said periods of excess ink discharge.

2. The structure according to claim 1, wherein said cells range fromabout .01 inch to about .07 inch in width.

3. The structure according to claim 1, wherein said element is generallytubular and said transfer surface is generally cylindrical and definedby a bore extending longitudinally through said control member andsurrounding said element and said feed forwardly of said element.

4. The structure according to claim 3, wherein said point and saidcapillary conduit are formed by an elongate generally cylindrical porouselement having a multiplicity of pores extending through its outersurface for communication with said generally cylindrical transfersurface forwardly of said tubular element.

5. The structure according to claim 1, wherein said cells are of varioussizes, the larger of said spaces comprising storage cells having lowercapillarity than said capillary conduit and remaining substantially freeof ink except under conditions of excess ink discharge into said conduitfrom said reservoir, the smaller of said spaces having greatercapillarity than said storage cells and providing a vein-like network ofcapillary passages through which ink is rapidly removed from saidconduit and carried throughout said control member to said storage cellsunder said conditions of excess ink discharge into said conduit fromsaid reservoir, said ink being withdrawn from said cells and returned tosaid conduit through said network upon subsequent removal of ink fromsaid conduit.

6. The structure according to claim 5, wherein said capillary conduitdefines at least one capillary ink channel having a width of about .001inch to about .005 inch, said cells range from about .01 inch to about.07 inch, and said other spaces range from about .001 inch to about .01inch.

7. The structure according to claim 6, wherein said matrix is formed ofpolyethylene.

8. The structure according to claim 6, wherein the void volume of saidstorage cells comprises between about 40% and about of the total voidvolume of said fluid control member.

References Cited UNITED STATES PATENTS 1,574,281 2/1926 Doyle. 2,554,6545/ 1951 Wittnebert. 2,684,052 7/ 1954 Rickmeyer. 2,921,558 1/1960 VonPlaten. 2,935,970 5/ 1960 Morse et al. 3,154,055 10/1964 Lawton.3,340,560 9/ 1967 Nakata. 2,282,840 5/1942 Wing 401-227 2,684,052 7/1954Rickmeyer 40l199 XR 2,935,970 5/1960 Morse et al 401227 3,340,560 9/1967Nakata 401198 FOREIGN PATENTS 941,439 11/1963 Great Britain.

1,384,182 1l/1964 France.

ROBERT W. MICHELL, Primary Examiner US. Cl. X.R. 40l-229

